Description: The purpose of this research was a proof of concept using a fan motor stator as transducer to monitor motor rotor and attached axial fan for mechanical motion. The proof was to determine whether bearing faults and fan imbalances could be detected in vane-axial fans using Motor Electrical Signature Analysis (MESA). The data was statistically analyzed to determine if the MESA systems could distinguish between baseline conditions and discrete fault frequencies for the three test conditions: bearing inner race defect, bearing outer race defect, and fan imbalance. The statistical conclusions for these proofs of concept were that MESA could identify all three faulted conditions.

Description: The objective of this research is to design, and determine the feasibility of, a telecommunication system for the city of Erdenet, Mongolia. The Mongolian Telecommunication Company, Telecommunication Company of Erdenet city, and the National Statistical Office of Mongolia provided the data required for telecommunication forecasting of Erdenet. The literature review and analysis of the telecommunication forecasting indicate the need for a model of a new Telecommunication system in Erdenet, Mongolia. The model, as indicated, should become a useful example for planning and updating the telecommunication system in Mongolia. The design of a proposed telecommunication network involves the following considerations: analyzing and forecasting telephone traffic, calculating the required number of channels, determining exchange locations, traffic matrix, and establishing a basic hierarchical structure.

Description: The Industrial Laser is firmly established in metalcutting as the tool of choice for many applications. The elevator division of Montgomery KONE Inc., in an effort to move towards quality, ontime, complete deliveries and 100% customer satisfaction, decided to invest in new equipment to improve manufacturing processes. A huge investment is proposed for a laser-cutting machine. It is the responsibility of Manufacturing Engineering to direct the management by justifying its benefits, which includes payback time and financial gains. Factors such as common line cutting, automated material handling system and cutting time were involved in justification of the initial cost of a laser-cutting machine. Comparative statistics on appropriate factors accurately determine and justify the initial cost of a laser-cutting machine.

Description: The objective of this study was to determine how a new experimental methodology for measuring Total-Harmonic-Distortion (THD) of operational amplifiers functioned when compared with two standard methodologies, and whether the new methodology offers any improvement in noise floor and dynamic range along with distortion canceling of the sine-wave source used in the testing. The new methodology (THD) is being tested against two standard methodologies: Spectral Analysis using a tuned receiver type Spectrum Analyzer with Notch Filter pre-processing, and a digitized Fast Fourier Transform (FFT) using Notch Filter pre-processing. The THD results appear to agree across all methodologies, and across all items of the sample within all methodologies, to within a percent or less. The distortion and noise canceling feature of the new methodology appeared to function as expected and in accordance with theory. The sample tested in the study consisted of thirty-five NE5534 operational amplifiers produced by Texas Instruments, Inc. and purchased from a local store. The NE5534 is a low-noise, low-distortion, operational amplifier that is widely used in industry and is representative of today's best audio amplifiers.

Description: Flow accelerated corrosion (FAC) is a major concern in the power industry as it causes thinning of the pipes by the dissolution of the passive oxide layer formed on the pipe surface. Present research deals with comparing the protection offered by the magnetite (Fe3O4) versus maghemite (γ-Fe2O3) phases thickness loss measurements. Fourier transform infrared spectroscopy (FTIR) is used in distinguishing these two elusive phases of iron oxides. Representative pipes are collected from high pressure steam extraction line of the secondary cycle of unit 2 of Comanche Peak Steam Electric Station (CPSES). Environmental scanning electron microscopy (ESEM) is used for morphological analysis. FTIR and X-ray diffraction (XRD) are used for phase analysis. Morphological analysis showed the presence of porous oxide surfaces with octahedral crystals, scallops and "chimney" like vents. FTIR revealed the predominance of maghemite at the most of the pipe sections. Results of thickness measurements indicate severe thickness loss at the bend areas (extrados) of the pipes.

Description: A dual, double-acting propulsion system is analyzed to determine how efficiently it can convert the potential energy available from liquid nitrogen into useful work. The two double-acting pistons (high- and low-pressure) were analyzed by using a Matlab-Simulink computer simulation to determine their respective mechanical efficiencies. The flow circuit for the entire system was analyzed by using flow circuit analysis software to determine pressure losses throughout the system at the required mass flow rates. The results of the piston simulation indicate that the two pistons analyzed are very efficient at transferring energy into useful work. The flow circuit analysis shows that the system can adequately maintain the mass flow rate requirements of the pistons but also identifies components that have a significant impact on the performance of the system. The results of the analysis indicate that the nitrogen propulsion system meets the intended goals of its designers.

Description: The primary objective of this study is to test the applicability to plastics of a fracture toughness testing tool developed for metals. The intent is to study pre-test conditioning of several plastic materials and the effect of the depth of the razor notch cut in the chevron notched fracture toughness test specimens. The study includes the careful preparation of samples followed by conditioning in various environments. Samples were subjected to laboratory air for a specific duration or to a controlled temperature-humidity condition as per the ASTM D1870. Some of the samples were subjected to vacuum conditioning under standard test specifications. Testing was conducted using the conventional three-point bend test as per ASTM D5045-95. ASTM E1304, which sets a standard for short rod and bar testing of metals and ceramics provides some basis for conducting chevron notched four-point bend tests to duplicate the toughness tool. Correlation of these results with the ASTM test samples is determined. The four-point bend test involves less specimen machining as well as time to perform the fracture toughness tests. This study of fracture toughness testing has potential for quality control as well as the fracture property determination.

Description: This thesis presents research toward the development of a simple inexpensive fracture toughness tool for polymeric materials. Experiments were conducted to test the specimen configuration and the fracture toughness tool against an established ASTM standard for polymer fracture toughness, D5045, and a commonly used four-point bend method. The materials used in this study were polycarbonate and high density polyethylene. Reductions in both the production time and the variability resulting from the preparation of the specimens were addressed through the use of specially designed fixtures. The effects from the razor cut depths used in the chevron notch were compared to the fracture toughness values obtained in order to determine the effect upon the validity of the fracture toughness.

Description: Commonly used amines in power industry, including morpholine, DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), and DMA (dimethylallylamine) were evaluated for their effect on AISI 1018 steel at 250oF. Samples were exposed to an autoclave containing amine added aqueous solution at pH of 9.5 for 1, 2, 4, 6, 8, and 12 hours. Morphology studies were carried using scanning electron microscope (SEM), phase analysis was done utilizing Fourier transform infrared spectroscopy (FTIR), and weight loss was performed to assess kinetics of oxidation. Control samples showed the highest metal dissolution rate. DBU showed the best performance in metal protection and SEM indicated the presence of a free-crack layer formed by fine particles in that set. FTIR showed that DBU apparently favored the formation of magnetite. It is believed that fine particles impede intrusion of aggressive ions into the metal surface by forming a barrier layer. FTIR demonstrated that DMA formed more oxyhydroxides, whereas morpholine presented magnetite to hematite transformation as early as 2 hours. SEM revealed that control and DMA produced acicular particles characteristic of oxyhydroxides while morpholine and DBU presented more equiaxed particles.

Description: Pulse oximeters are used in operating rooms and recovery rooms as a monitoring device for oxygen in the respiratory system of the patient. The advantage of pulse oximeters over other methods of oxygen monitoring is that they are easy to use and they are non-invasive, which means it is not necessary break the skin to extract blood for information to be obtained. The standard for the measurement of partial pressure of CO2 and O2 is an arterial blood gas analysis (ABG). However routine monitoring using this method on a continuous basis is impractical since it is slow, painful and invasive. Measuring carbon dioxide is critical to preventing ailments such as carbon dioxide poisoning or hypoxia. The problem is, currently there is no known effective non-invasive method for accurately measuring carbon dioxide in the body to properly assess the adequacy of ventilation. The objective of this study was to experimentally use spectroscopy in the visible spectrum and the principles of operation of a pulse oximeter to incorporate a method of non-invasive real-time carbon dioxide monitoring that is as quick and easy to use.

Description: The purpose of this research was to determine which of the commonly used wireless telecommunication site concealment materials has the least effect on signal potency. The tested materials were Tuff Span® fiberglass panels manufactured by Enduro Composite Systems, Lexan® XL-1 polycarbonate plastic manufactured by GE Corporation and Styrofoam polystyrene board manufactured by The Dow Chemical Company. Testing was conducted in a double electrically isolated copper mesh screen room at the University of North Texas Engineering Technology Building in Denton, Texas. Analysis of the data found no differences exist between the radio frequency transmissiveness of these products at broadband personal communication service frequencies. However, differences in the signal do exist with regards to the angle of incidence between the material and the transmitting antenna.

Description: The purpose of this research is to determine the linearity and monotonicity of the THS5651IDW digital to analog converter (DAC), a prototype of the future Texas Instruments TLV5651, 10-bit, 125 MHz communication DAC. Testing was conducted at the Texas Instruments facility on Forest Lane, Dallas, Texas. Texas Instruments provided test equipment, software and laboratory space to obtain test data. Analysis of the data found the DAC to be monotonic since the magnitude of the differential nonlinearity (DNL) was less than ± 1 least significant bit (LSB) and the integral nonlinearity (INL) was less than ± 0.5 LSB. The study also showed that the DAC has primarily negative DNL although the DNL is well within the desired specification.

Description: A rectifier is an electrical device, comprising one or more semiconductor devices arranged for converting alternating current to direct current by blocking the negative or positive portion of the waveform. The purpose of this study would be to evaluate dynamic and static electrical characteristics of rectifier chips fabricated with (a) DY8 process and (b) YI8 process and compare them with the existing DI8 process rectifiers. These new rectifiers were tested to compare their performance to meet or exceed requirements of lower forward voltages, leakage currents, reverse recovery time, and greater sustainability at higher temperatures compared to diodes manufactured using boron as base (DI8 process diodes) for similar input variables.

Description: This thesis presents a novel ZnO-hydrogel based fluorescent colloidal semiconductor nanomaterial system for potential bio-medical applications such as bio-imaging, cancer detection and therapy. The preparation of ZnO nanoparticles and their surface modification to make a biocompatible material with enhanced optical properties is discussed. High quality ZnO nanoparticles with UV band edge emission are prepared using gas evaporation method. Semiconductor materials including ZnO are insoluble in water. Since biological applications require water soluble nanomaterials, ZnO nanoparticles are first dispersed in water by ball milling method, and their aqueous stability and fluorescence properties are enhanced by incorporating them in bio-compatible poly N-isopropylacrylamide (PNIPAM) based hydrogel polymer matrix. The optical properties of ZnO-hydrogel colloidal dispersion versus ZnO-Water dispersion were analyzed. The optical characterization using photoluminescence spectroscopy indicates approximately 10 times enhancement of fluorescence in ZnO-hydrogel colloidal system compared to ZnO-water system. Ultrafast time resolved measurement demonstrates dominant exciton recombination process in ZnO-hydrogel system compared to ZnO-water system, confirming the surface modification of ZnO nanoparticles by hydrogel polymer matrix. The surface modification of ZnO nanoparticles by hydrogel induce more scattering centers per unit area of cross-section, and hence increase the luminescence from the ZnO-gel samples due to multiple path excitations. Furthermore, surface modification of ...

Description: Cellular radio communication involves wireless transmission and reception of signals at radio frequencies (RF). Base stations house equipment critical to the transmission and reception of signals. Power amplifier (PA) is a crucial element in base station assembly. PAs are expensive, take up space and dissipate heat. Of all the elements in the base station, it is difficult to design and operate a power amplifier. New designs of power amplifiers are constantly tested. One of the most important components required to perform this test successfully is a circuit simulator model of an entire communication system that generates a standard test signal. Standard test signals 524,288 data points in length require 1080 hours to complete one test of a PA model. In order to reduce the time taken to complete one test, a 'simulated test signal,' was generated. The objective of this study is to develop an algorithm to generate this 'simulated' test signal such that its characteristics match that of the 'standard' test signal.

Description: In the immediate future, multimedia product distribution through the Internet will become main stream. However, it can also have the side effect of unauthorized duplication and distribution of multimedia products. That effect could be a critical challenge to the legal ownership of copyright and intellectual property. Many schemes have been proposed to address these issues; one is digital watermarking which is appropriate for image and video copyright protection. Videos distributed via the Internet must be processed by compression for low bit rate, due to bandwidth limitations. The most widely adapted video compression standard is MPEG-4. Discrete cosine transform (DCT) domain watermarking is a secure algorithm which could survive video compression procedures and, most importantly, attacks attempting to remove the watermark, with a visibly degraded video quality result after the watermark attacks. For a commercial broadcasting video system, real-time response is always required. For this reason, an FPGA hardware implementation is studied in this work. This thesis deals with video compression, watermarking algorithms and their hardware implementation with FPGAs. A prototyping VLSI architecture will implement video compression and watermarking algorithms with the FPGA. The prototype is evaluated with video and watermarking quality metrics. Finally, it is seen that the video qualities ...

Description: A cryogenic thermoelectric generator is proposed to increase the efficiency of a vehicle propulsion system that uses liquid nitrogen as its fuel. The proposed design captures some of the heat required for vaporizing or initial heating of the liquid nitrogen to produce electricity. The thermoelectric generator uses pressurized liquid nitrogen as its cold reservoir and ambient air as the high-temperature reservoir to generate power. This study concentrated on the selection of thermoelectric materials whose properties would result in the highest efficiency over the operating temperature range and on estimating the initial size of the generator. The preliminary selection of materials is based upon their figure of merit at the operating temperatures. The results of this preliminary design investigation of the cryogenic thermoelectric generator indicate that sufficient additional energy can be used to increase overall efficiency of the thermodynamic cycle of a vehicle propulsion system.

Description: Nanoindentation has become a widely used technique to measure the mechanical properties of materials. Due to its capability to deform materials in micro- and nano-scale, nanoindentation has found more applications in characterizing the deformation behavior and determining the mechanical properties of thin films and coatings. This research deals with the characterization of samples received from Center for Advanced Microstructures and Devices (CAMD) and Integran Technologies Inc., Toronto, Canada and the objective of this investigation was to utilize the experimental data obtained from nanoindentation to determine the deformation behavior, mechanical properties of thin films on substrates and bulk materials, and the effect of geometrically different indenters (Berkovich, cubecorner, and conical). X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM) analysis were performed on these materials to determine the crystal orientation, grain size of the material, and also to measure any substrate effects like pile-up or sin-in respectively. The results indicate that indentation size effect (ISE) strongly depends on shape of the indenter and less sensitive to penetration depth where as the hardness measurements depends on shape of indenter and depth of penetration. There is a negligible strain rate dependency of hardness at deeper depths ...

Description: Within the nuclear industry, there have been numerous instances of radio transmissions interfering with sensitive plant equipment. Instances documented vary from minor instrument fluctuations to major plant transients including reactor trips. With the nuclear power industry moving toward digital technologies for control and reactor protection systems, concern exists regarding their potential susceptibility to contemporary wireless telecommunications technologies. This study evaluates the susceptibility of Comanche Peak's planned turbine controls upgrade to IEEE 802.11 compliant wireless radio emissions. The study includes a review of previous research, industry emissions standards, and technical overview of the various IEEE 802.11 protocols and details the testing methodology utilized to evaluate the digital control system. The results of this study concluded that the subject digital control system was unaffected by IEEE 802.11 compliant emissions even when the transmitter was in direct contact with sensitive components.

Description: Lighted push button switches and indicators serve many purposes in cockpits, shipboard applications and military ground vehicles. The quality of lighting produced by switches is vital to operators' understanding of the information displayed. Utilizing LED technology in lighted switches has challenges that can adversely affect lighting quality. Incomplete data exists to educate consumers about potential differences in LED switch performance between different manufacturers. LED switches from four different manufacturers were tested for six attributes of lighting quality: average luminance and power consumption at full voltage, sunlight readable contrast, luminance contrast under ambient sunlight, legend uniformity, and dual-color uniformity. Three of the four manufacturers have not developed LED push button switches that meet lighting quality standards established with incandescent technology.

Description: Modern studies on charge transfer reaction and conductivity measurements of DNA have shown that the electrical behavior of DNA ranges from that of an insulator to that of a wide bandgap semiconductor. Based on this property of DNA, a metal-semiconductor-metal photodetector is fabricated using a self-assembled layer of deoxyguanosine derivative (DNA base) deposited between gold electrodes. The electrodes are lithographically designed on a GaN substrate separated by a distance L (50nm < L < 100nm). This work examines the electrical and optical properties of such wide-bandgap semiconductor based biomaterial systems for their potential application as photodetectors in the UV region wherein most of the biological agents emit. The objective of this study was to develop a biomolecular electronic device and design an experimental setup for electrical and optical characterization of a novel hybrid molecular optoelectronic material system. AFM results proved the usage of Ga-Polar substrate in conjugation with DG molecules to be used as a potential electronic based sensor. A two-terminal nanoscale biomolectronic diode has been fabricated showing efficient rectification ratio. A nanoscale integrated ultraviolet photodetector (of dimensions less than 100 nm) has been fabricated with a cut-off wavelength at ~ 320 nm.

Description: Group- III nitride based semiconductors have emerged as the leading material for short wavelength optoelectronic devices. The InGaN alloy system forms a continuous and direct bandgap semiconductor spanning ultraviolet (UV) to blue/green wavelengths. An ideal and highly efficient light-emitting device can be designed by enhancing the spontaneous emission rate. This thesis deals with the design and fabrication of a visible light-emitting device using GaN/InGaN single quantum well (SQW) system with enhanced spontaneous emission. To increase the emission efficiency, layers of different metals, usually noble metals like silver, gold and aluminum are deposited on GaN/InGaN SQWs using metal evaporator. Surface characterization of metal-coated GaN/InGaN SQW samples was carried out using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Photoluminescence is used as a tool for optical characterization to study the enhancement in the light emitting structures. This thesis also compares characteristics of different metals on GaN/InGaN SQW system thus allowing selection of the most appropriate material for a particular application. It was found out that photons from the light emitter couple more to the surface plasmons if the bandgap of former is close to the surface plasmon resonant energy of particular metal. Absorption of light due to gold reduces the ...

Description: Cubic boron nitride (cBN) synthesis has gained lot of interest during the past decade as it offers outstanding physical and chemical properties like high hardness, high wear resistance, and chemical inertness. Despite of their excellent properties, every application of cBN is hindered by high compressive stresses and poor adhesion. The cost of equipment is also high in almost all the techniques used so far. This thesis deals with the synthesis of cubic phase of boron nitride on Si (100) wafers using electron beam evaporator, a low cost equipment that is capable of depositing films with reduced stresses. Using this process, need of ion beam employed in ion beam assisted processes can be eliminated thus reducing the surface damage and enhancing the film adhesion. Four sets of samples have been deposited by varying substrate temperature and the deposition time. scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) techniques have been used to determine the structure and composition of the films deposited. X-ray diffraction (XRD) was performed on one of the samples to determine the thickness of the film deposited for the given deposition rate. Several samples showed dendrites being formed as ...

Description: Nanoindentation is a widely used technique to measure the mechanical properties of films with thickness ranging from nanometers to micrometers. A much better understanding of the contact mechanics is obtained mostly through finite element modeling. The experiments were modeled using the software package Nano SP1 that is based on COSMOSM (Structural Research & Analysis Corp, www.cosmosm.com), a finite element code. The fundamental material properties affecting pile-up are the ratio of the effective modulus to yield stress Eeff/σ and the work hardening behavior. Two separate cases of work hardening rates were considered; one with no work hardening rate and other with a linear work hardening rate. Specifically, it is observed that pile up is large only when hf/hmax is close to one and degree of work hardening rate is small. It should also be noted that when hf/hmax < 0.7 very little pile-up is observed no matter what the work-hardening behavior of the material. When pile-up occurs the contact area is greater than that predicted by the experimental methods and both the hardness and modulus are overestimated. In this report the amount by which these properties are overestimated are studied and got to be around 22% approx. Bluntness of the tip ...